Filled polymeric materials have been known to provide decorative and protective surfaces to walls. For instance, it has been known to coat masonry units filled with polyesters and to form walls therefrom. The basic patent on the use of polyester as coating for masonry units is U.S. Pat. No. 2,751,775 to Sergovic and assigned to the assignee of the present invention. Over the years, a number of improvements in the coating compositions for the masonry building units have been developed. For instance, U.S. Pat. No. 3,328,231 to Sergovic and assigned to the assignee of the present invention, discloses a glazed masonry building block of a cured composition of unsaturated polyester resin and sand in which the sand comprises at least 50% by weight of the coating composition. The unsaturated polyester is derived from a reaction between a dicarboxylic acid such as phthalic, maleic, fumaric, adipic, pimelic, suberic, itaconic, citraconic, succinic acids, and/or an anhydride thereof, and a polyhydric alcohol such as ethylene glycol, diethylene glycol, and propylene glycol. Also present in such compositions is an unsaturated monomer, such as methyl methacrylate styrene, diallyl phthalate, t-butyl styrene, and alphamethyl styrene. Furthermore, U.S. Pat. No. 4,031,289 to Sergovic discloses coated masonry building blocks, articles and compositions therefore that employ resinous pigments and chemicals in combination with various resinous compositions to provide stain resistance when subjected to high moisture conditions and/or staining media. The disclosures of the above-mentioned U.S. Pat. Nos. 2,751,775; 3,328,231 and 4,031,289 are incorporated herein by reference.
Constructing walls with glazed masonry building units presents particular problems with respect to the formation of outside corners of the wall structure. For example, glazed cinder or concrete blocks at corners and intersecting wall planes must be glazed on more than one side, in particular, one face and one end or one face and one top provided they are intersecting, in order for the glazed material to show when turning a corner.
Known attempts to construct outside corners using glazed masonry building units involved forming the corner from one or more blocks having flat surfaces. The corner, which may be formed from flat surfaces on the exterior of one more blocks, may be a sharp 90.degree. corner formed by the intersection of the exterior surfaces of the two walls. Alternatively, the corner may be formed from one or more angled flat surfaces formed by one or more exterior walls on adjoining masonry building units. For example, see FIGS. 1-4. Another attempt to overcome the problems associated with constructing outside corners is disclosed in U.S. Pat. No. 4,329,822 to Russell and assigned to the assignee of the present application. In particular, U.S. Pat. No. 4,329,822 discloses a corner wall facing unit that includes a unit that is not supported by a concrete block and must be supported using a non-block supported wall system or wire meshing and is time-consuming to erect. Although such a system has been quite effective such non-self-supporting units tend to be relatively heavy for their size which requires the use of temporary wedges to prevent slippage and sagging in the mortar used between the wall unit during erection. Also, such units require special insulation care, and do not assure structural integrity.
Moreover, turning a corner, e.g.--a 90.degree. corner or more, has been carried out by employing a single piece angled block in conjunction with a glazed straight wall unit (see FIG. 3). Such a corner would be used to create a wall angle in the exposed face by employing one angle glazed block and will always be connected to a straight wall unit without the use of a second corner piece or angled glazed block. The return employed on these prior angle and glazed blocks is relatively deep, i.e. at least about three and three quarters inches. The use of such a single piece angled glazed block not only requires a fill piece adding to the complexity of the arrangement. The angled glazed blocks are merely an angled version of the 90.degree., 4 inch, 6 inch, 8 inch, or 12 inch single core units.
Constructing walls with glazed masonry building units also presents particular problems with respect to the formation of the outside corner of the wall structure. For example, glazed cinder or concrete blocks at corners and intersecting wall planes must be glazed on more than one side, in particular when one face and one end or one face and one top provided that they are intersecting, in order for the glaze material to shown when turning a corner. However, attempts to glaze two intersecting sides of a masonry block have not been entirely successful and have suffered from a number of problems. For example, the percent of factory culls or rejects generated when making a corner or cap block with two more surfaces glazed simultaneously is greater than the percent of culls generated when glazing a single face or plane to form a straight wall unit (referred to in the art as "stretchers").
When making a unit with two intersecting glazed planes, a mold which has two intersecting planes is used. The space between the vertical plane of the mold and the concrete block requires special care when filling to assure the removal of entrapped air in the glazing material. This results in air bubbles which become pin holes in the return end of corner units. Also, the differences in sand settlement can cause lines at the intersecting planes of the corner.
Rejected glazed corner blocks result in about 5 to about 10% loss as compared to only about a 0.5% to a 2% loss for coated "stretchers". In particular, defects in the finished products are manifested in the formation of unsightly lines at the intersecting lanes of the decorative surfaces of the corner units, unsightly pin holes and differences in the color appearance of the intersecting surface planes of such blocks.